The present invention relates to a support assembly for a planetary gear train type selvage unit (hereinafter referred to "a planetary-type selvage unit") on a loom. More particularly, the invention relates to improvements in suitability of such a planetary-type selvage unit to accommodate a shift in production scheme, more specifically to a change in type of fabrics, on a weaving loom.
In general, a planetary-type selvage unit is fixed at its lateral ends to a framework of a loom at positions corresponding to the reeding width of fabrics to be woven on the loom. The distance between the fixed lateral ends of the planetary-type selvage unit is smaller than the width of heald frames used for weaving the fabrics.
When warps on a warp beam are fully consumed because of the advance of weaving or because the production scheme is to be shifted, an old warp beam combined with an old set of elements for passing warps delivered from the old warp beam has to be exchanged with a new warp beam combined with a new set of elements for passing warps from the new warp beam. This exchange is generally called "looming operation". The set of the element generally includes heald frames, a dropper box and a reed. In such a looming operation, the new set of elements is mounted to the loom sequentially from the warp let-off motion side to the cloth take-up side on the loom.
As is well known, a planetary-type selvage unit is mounted to a loom at a position closer to the let-off motion side than the position at which the heald frames are mounted to the loom. Consequently, the planetary-type selvage unit is mounted to the loom before mounting of the heald frames. So, for mounting the heald frames to the loom, the heald frames must be transported forwards, i.e. towards the take-up side, across a space over the planetary-type selvage unit.
Conventionally, the planetary-type selvage unit is fixedly mounted to the loom without any possibility of changing its height. Thus, the height of the planetary-type selvage unit remains unchanged throughout the weaving operation and the looming operation. As a consequence, during the looming operation, the heald frames need to be held high above the planetary-type selvage unit to avoid an undesired crashings into each other during their forward transportation.
In the design of a carriage used for automatic looming operation, the carriage has a construction capable of having the heald frame at a high position to enable the above-described transportation above the planetary-type selvage unit. In other words, the construction of the carriage is un-desirably enlarged. In addition, such a top-heavy construction impairs operation stability of the carriage which is quite un-welcome from the viewpoint of operation safety. Further an increase in manufacturing cost and low operability are caused by such a top heavy construction.
When looming operation is carried out manually, the heald frames must be lifted high above the planetary-type selvage unit, which entails increased labor associated with low level of operation safety.
When an accessory such as an overlay-type Dobby shedding machine is arranged overhead the loom, a remaining space above the loom is too small to transport the heald frames in an upright position. Thus, the heald frames have to be kept in a somewhat inclined or horizontal position during the forward transportation above the planetary-type selvage unit. The heald frames are usually carried on a carriage in an upright position. Thus, upon unloading from the carriage, the heald frames have to be changed to a horizontal position by manual operation, conveyed across a space overhead the planetary-type selvage unit, and returned to the upright position after completion of conveyance. Such a complicated manual operation poses increased load on an operator and necessitates elongated operation time.
From the foregoing, it is well understood that the conventional planetary-type selvage unit is very much unsuited for looming operation and, as a consequence, very poorly suited to accommodate a shift in production scheme.